The present invention generally relates to laser-assisted material processing. The invention particularly relates to systems and methods for performing microscale laser-assisted machining.
With growing miniaturization of products capable of shrinking size and increasing complexity in many applications, the demand for high-precision manufacture of miniature parts (e.g., a few microns in size) having complex features has expanded to advanced engineering materials such as ceramics (including ceramic matrix composites (CMCs)), stainless steels and high temperature alloys. Micromachining techniques such as laser machining, micro milling, rotary ultrasonic machining, conventional grinding, ultrasonic slurry-based machining, micro abrasive waterjet machining, and electrical discharge machining have been considered. Particular challenges include low material removal rates and generated (machined) surfaces having less than desired properties, for example, for purposes of subsequent coating. Due to its great process flexibility, micro milling has been proposed as a particularly promising technology for the manufacture of various engineering products made of advanced engineering materials with high accuracy. However, conventional micro milling of difficult-to-machine materials still remains a technological challenge in industry due to short tool life when applied to advanced engineering materials, poor or compromised machined surface integrity, and increased risk of inducing flaws in advanced engineering materials with low fracture toughness. In addition, some advanced engineering materials react negatively to the presence of water, oil, and/or certain elements and/or compounds within cutting fluids of the types typically used in micro milling processes.
Laser-assisted micromachining (LAMM) technologies refer to micromachining techniques that employ a laser beam to assist material removal performed by another instrumentality, e.g., a cutting tool, and therefore differs from laser machining LAMM has been introduced to improve the machinability of materials with high strength, good corrosion, and wear resistance. While it is highly desirable to develop a micromachining system for processing engineering materials with good precision, technological challenges remain in integrating a laser in a miniature micromachining system while maintaining high machined quality and decreasing the tool wear to achieve longer tool life. Due to the very limited space and the nature of laser beam sources, a high incidence angle is usually incorporated in laser-assisted micromachining systems (as used herein, “incidence angle” and “angle of incidence” of a laser beam will be used to refer to the angle between a perpendicular to a surface impinged by a laser beam and the path of the laser beam at the point of impingement). To simplify micromachining operations, laser beam delivery is often fixed in space and the focused laser spot size cannot be adjusted. Such laser beam delivery designs often find limited use for many machining processes, for example, machining deep slots, pockets, or contouring, and may not be able to fully exploit the advantages of laser-assisted micromachining.
Therefore, there is a need for laser-assisted micromachining systems that are capable of greater flexibility in terms of adjusting the laser beam delivery path and laser spot size in order to extend laser-assisted micromachining to more machining (cutting) processes.